Many dislocated fractures of long bones, in particular of the lower extremities, are currently treated surgically (osteosynthesis). Every osteosynthesis typically includes preoperative, intraoperative and postoperative medical imaging. Preoperative and postoperative medical imaging is used for diagnosis and planning, and control, respectively. Intraoperative medical imaging, which is commonly achieved using a mobile fluoroscope, provides an optical feedback to control the manipulation of the fracture fragments, appropriate alignment and implant positioning.
In fractures of the lower limbs there are mainly two treatment options: closed reduction internal fixation (CRIF) and open reduction internal fixation (ORIF). In CRIF the reduction is carried out without direct exposure and direct visualization of the fracture. The only visual information about the fractured bone is provided by intraoperative fluoroscopy. In contrast, in ORIF, the fracture is exposed surgically by dissecting the overlaying soft tissues. Exposing the fracture, the surgeon can reduce it under direct vision controlling only the end result with the fluoroscope.
For the majority of shaft fractures of tibia and femur, CRIF using intramedullary nails is the treatment of choice. In other cases, for instance where closed reduction is impossible or in institutions where no image intensifier is available, ORIF is used. Closed reduction is preferred because it is less invasive, more respectful of soft tissues, it lowers the risk of greater blood loss, interferes less with the biology of fracture healing, and shows better cosmetic results. However, CRIF is technically more demanding for the surgeon and exposes both the patient and the medical staff to higher radiation doses.
Possible complications of fixing the femoral or tibial shaft include angular and/or rotational malalignment of the fracture fragments as well as incorrect restoration of the bone length. Such complications can cause false posture, or restricted movement and/or excessive strain on the patient's joint structures due to a significant change in the natural anatomical structure and biomechanics. In many cases, the above-mentioned complications could be avoided, if improved intraoperative visualization modalities were available.
A common intraoperative fluoroscope can visualize a circular region with a diameter of a maximum of 12-18 cm. Due to this limitation, the entire fractured bone can only be partially visualized. The shafts of tibia and femur have nearly no morphological or structural inhomogeneities. Consequently, the rotational alignment of the fracture fragments can not be readily determined from medical images containing the shaft alone. The visualization of a proper alignment of the fracture fragments indicates the desirability fo a representation of the whole bone including the shaft and the morphologically inhomogeneous epiphyses, from which the rotation of the fragments and the bone length can be determined
What is therefore needed is an improved method and apparatus for properly positioning fractured bone fragments without having to use open reduction internal fixation.